Thermal conductivities of (ZrxPu(1-x)/2Am(1-x)/2)N solid solutions

The thermal conductivity of Zr-based transuranium (TRU) nitride solid solutions is important for designing subcritical cores in nitride-fueled ADS. Some results have been reported concerning the thermal conductivities of (Zr,Pu)N. However, there have been no experimental data on the thermal conductivities of Zr-based nitride solid solutions containing MA. In this study, the authors prepared sintered samples of (ZrxPu(1-x)/2Am(1-x)/2)N (x=0.0, 0.58, 0.80) solid solutions. The thermal diffusivity and heat capacity of (ZrxPu(1-x)/2Am(1-x)/2)N solid solutions were measured using a laser flash method and drop calorimetry, respectively. Thermal conductivities were determined from the measured thermal diffusivities, heat capacities and bulk densities over a temperature range of 473 to 1473 K. The thermal conductivities of (Zr0.58Pu0.21Am0.21)N and (Zr0.80Pu0.10Am0.10)N solid solutions were found to be higher than that of (Pu0.5Am0.5)N due to the high thermal conductivity of ZrN as the principal component, although they were lower than that of ZrN due to the impurifying effect of the transuranium elements. Thus, the thermal conductivities of (ZrxPu(1-x)/2Am(1-x)/2)N solid solutions increased with increasing ZrN concentration. Moreover, in order to help to promote the design study of nitride-fueled ADS, the thermal conductivity of the (ZrxPu(1-x)/2Am(1-x)/2)N solid solutions were fitted to an equation using the least squares method. (author)